The issue is related to a heap out-of-bounds read in the code handling the end-of-response for SMTP. This occurs when the buffer passed to `smtp endofresp()` is not null terminated and contains no character ending the parsed number, and `len` is set to 5. As a result, the `strtol()` call reads beyond the allocated buffer, but the read contents are not returned to the caller. The exploitation of this issue may allow a remote attacker to impact the confidentiality, integrity, and availability of protected information, potentially leading to a denial of service.